Cascade hydropower plants can improve the system security and water utilization efficiency by hydraulic and electricity compensation. By developing the daily electricity generation plan for cascade hydropower plants, the loads of generators of the plant and their open/close status can be determined while satisfying the daily available water and grid demand, thus increasing the water utilization efficiency and maximizing economic benefits.
The steps of developing traditional daily generation plan for cascade hydropower plants are as follows: (1) input data of short-term runoff forecast, and determine the daily available water for each reservoir according to their long-term operational results; (2) take the maximum electricity generation benefits as one of the optimization objectives; (3) determine the constraints for optimizing the cascade hydropower plants; and (4) derive the daily electricity generation plan by optimization based on the above steps.
The problems of existing methods are as follows: (1) The constraints for the gird demand are neglected in the optimization, thus failing to generate a bimodal load curve, and (2) it is difficult to use the dynamic programming algorithm for the optimization model due to the constraints of the open/close state for the hydropower plants generators.